1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Copyright (C) 2017 Sean Young <sean@mess.org>
6 #include <linux/kernel.h>
7 #include <linux/module.h>
8 #include <linux/gpio/consumer.h>
9 #include <linux/delay.h>
10 #include <linux/slab.h>
12 #include <linux/platform_device.h>
13 #include <media/rc-core.h>
15 #define DRIVER_NAME "gpio-ir-tx"
16 #define DEVICE_NAME "GPIO IR Bit Banging Transmitter"
19 struct gpio_desc *gpio;
21 unsigned int duty_cycle;
24 static const struct of_device_id gpio_ir_tx_of_match[] = {
25 { .compatible = "gpio-ir-tx", },
28 MODULE_DEVICE_TABLE(of, gpio_ir_tx_of_match);
30 static int gpio_ir_tx_set_duty_cycle(struct rc_dev *dev, u32 duty_cycle)
32 struct gpio_ir *gpio_ir = dev->priv;
34 gpio_ir->duty_cycle = duty_cycle;
39 static int gpio_ir_tx_set_carrier(struct rc_dev *dev, u32 carrier)
41 struct gpio_ir *gpio_ir = dev->priv;
46 gpio_ir->carrier = carrier;
51 static void delay_until(ktime_t until)
54 * delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on
55 * m68k ndelay(s64) does not compile; so use s32 rather than s64.
60 delta = ktime_us_delta(until, ktime_get());
64 /* udelay more than 1ms may not work */
65 delta = min(delta, 1000);
70 static void gpio_ir_tx_unmodulated(struct gpio_ir *gpio_ir, uint *txbuf,
80 for (i = 0; i < count; i++) {
81 gpiod_set_value(gpio_ir->gpio, !(i % 2));
83 edge = ktime_add_us(edge, txbuf[i]);
87 gpiod_set_value(gpio_ir->gpio, 0);
90 static void gpio_ir_tx_modulated(struct gpio_ir *gpio_ir, uint *txbuf,
95 * delta should never exceed 0.5 seconds (IR_MAX_DURATION) and on
96 * m68k ndelay(s64) does not compile; so use s32 rather than s64.
100 unsigned int pulse, space;
102 /* Ensure the dividend fits into 32 bit */
103 pulse = DIV_ROUND_CLOSEST(gpio_ir->duty_cycle * (NSEC_PER_SEC / 100),
105 space = DIV_ROUND_CLOSEST((100 - gpio_ir->duty_cycle) *
106 (NSEC_PER_SEC / 100), gpio_ir->carrier);
112 for (i = 0; i < count; i++) {
115 edge = ktime_add_us(edge, txbuf[i]);
119 ktime_t last = ktime_add_us(edge, txbuf[i]);
121 while (ktime_before(ktime_get(), last)) {
122 gpiod_set_value(gpio_ir->gpio, 1);
123 edge = ktime_add_ns(edge, pulse);
124 delta = ktime_to_ns(ktime_sub(edge,
128 gpiod_set_value(gpio_ir->gpio, 0);
129 edge = ktime_add_ns(edge, space);
130 delta = ktime_to_ns(ktime_sub(edge,
141 static int gpio_ir_tx(struct rc_dev *dev, unsigned int *txbuf,
144 struct gpio_ir *gpio_ir = dev->priv;
147 local_irq_save(flags);
148 if (gpio_ir->carrier)
149 gpio_ir_tx_modulated(gpio_ir, txbuf, count);
151 gpio_ir_tx_unmodulated(gpio_ir, txbuf, count);
152 local_irq_restore(flags);
157 static int gpio_ir_tx_probe(struct platform_device *pdev)
159 struct gpio_ir *gpio_ir;
160 struct rc_dev *rcdev;
163 gpio_ir = devm_kmalloc(&pdev->dev, sizeof(*gpio_ir), GFP_KERNEL);
167 rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);
171 gpio_ir->gpio = devm_gpiod_get(&pdev->dev, NULL, GPIOD_OUT_LOW);
172 if (IS_ERR(gpio_ir->gpio)) {
173 if (PTR_ERR(gpio_ir->gpio) != -EPROBE_DEFER)
174 dev_err(&pdev->dev, "Failed to get gpio (%ld)\n",
175 PTR_ERR(gpio_ir->gpio));
176 return PTR_ERR(gpio_ir->gpio);
179 rcdev->priv = gpio_ir;
180 rcdev->driver_name = DRIVER_NAME;
181 rcdev->device_name = DEVICE_NAME;
182 rcdev->tx_ir = gpio_ir_tx;
183 rcdev->s_tx_duty_cycle = gpio_ir_tx_set_duty_cycle;
184 rcdev->s_tx_carrier = gpio_ir_tx_set_carrier;
186 gpio_ir->carrier = 38000;
187 gpio_ir->duty_cycle = 50;
189 rc = devm_rc_register_device(&pdev->dev, rcdev);
191 dev_err(&pdev->dev, "failed to register rc device\n");
196 static struct platform_driver gpio_ir_tx_driver = {
197 .probe = gpio_ir_tx_probe,
200 .of_match_table = of_match_ptr(gpio_ir_tx_of_match),
203 module_platform_driver(gpio_ir_tx_driver);
205 MODULE_DESCRIPTION("GPIO IR Bit Banging Transmitter");
206 MODULE_AUTHOR("Sean Young <sean@mess.org>");
207 MODULE_LICENSE("GPL");